Many amidoxime compounds can be made by cyanoethylation of a nucleophile with acrylonitrile prior the conversion to amidoxime by reacting with hydroxylamine. The nucelophile can include, but is not limited to, the following:                compounds containing one or more —OH or —SH groups, such as water, alcohols, phenols, oximes, hydrogen sulphide and thiols;        compounds containing one or more —NH— groups, e.g. ammonia, primary and secondary amines, hydrazines, and amides;        ketones or aldehydes possessing a —CH—, —CH2—, or —CH3 group adjacent to the carbonyl group; and        compounds such as malonic esters, malonamide and cyanoacetamide, in which a —CH— or —CH2— group is situated between —CO2R, —CN, or —CONH— groups.        
The cyanoethylation process usually requires a strong base as a catalyst. Most often such bases are alkali metal hydroxides such as, e.g., lithium hydroxide, sodium hydroxide and potassium hydroxide. These metals, in turn, can exist as impurities in the amidoxime compound solution. The existence of such metals in the amidoxime compound solution is not acceptable for use in electronic, and more specifically, semiconductor manufacturing processes and as a stabilizer for hydroxylamine freebase and other radical sensitive reaction chemicals.
Chemical compounds which contain one or more unsaturated groups have a pronounced tendency to undergo free-radical polymerization. Such compounds are used as monomers for the targeted preparation of polymers, e.g. by free-radical polymerization. At the same time, the pronounced tendency to undergo free-radical polymerization is a disadvantage in so far as undesired, spontaneous free-radical polymerization can occur both during storage and during chemical and/or physical processing, e.g. by distillation or rectification, of the unsaturated compounds, in particular under the action of heat and/or light. Such uncontrolled free-radical polymerizations present a considerable hazard potential and frequently proceed in an explosive manner. In the distillation of mixtures comprising unsaturated compounds, polymer formed in an uncontrolled manner can, for example, deposit on the surface of the vaporizer, where the tendency to form polymer is increased as a result of the high temperatures, and thereby cause an undesirable reduction in the heat transfer. Polymer which is formed can also block the internals in rectification columns, which causes undesirable pressure drops. Finally, the rectification process has to be interrupted to remove the polymer which has been formed.
The free radical polymerization is usually caused by trace metal impurities; it is highly desirable for a chelating agent with low metal ions to be effectively function as radical quencher to inhibit the undesirable polymerization reaction.
The manufacture of advanced electronic devices such as semiconductor components historically has used thin film deposition and etching processes to construct three-dimensional circuits, typically using aluminum conductors and silica (SiO2) insulation layers. Connections between layers are constructed using optical lithography, photoresist patterning and plasma etching to create a complex and extremely small-scale pattern of connecting holes through the silica insulating layers. Several hundred steps may be required for the manufacture of some semiconductor chips, with exacting requirements at each step. The constant need for increased device performance along with microminiaturization is presently leading to a switch to copper conductors and better insulating (low-k dielectric) films such as doped silica, fluorinated or porous insulation layers. For the Al/SiO2 systems, post-etch cleaning formulations relied on formulations containing such chemicals as hydroxylamine or other solvents. These formulations, however, do not meet the requirements of the newer advanced chip designs and materials of construction due to high trace metal impurities.
In addition, there is a desire in the industry to find more effective and environmentally friendly aqueous-based cleaners. For instance, a dilute aqueous amidoxime compound has been discovered by Lee, which is disclosed in U.S. Patent Application No. 61/000,727 to be a highly effective chelating agent for cleaning application in the manufacture of modern semiconductor processes including front end of the line, back end of the line, post chemical mechanical planarization cleaning steps, and in slurry system for chemical mechanical planarization process.
In modern semiconductor chips, features such as conducting “via” or holes, are of the order of 60 nm or smaller in diameter. Another requirement during the many stages of the construction of a semiconductor chip is that the levels of metals, particularly metal ions in cleaning formulations must be limited to concentrations at the ppb, or ppb level. Residual metal contamination left in the substrate surface can result in unwanted conductive pathways or alter the composition and, therefore, the electrical performance of various film layers, resulting in a diminished yield of micro-assemblies meeting the rigid final performance specifications. In semiconductor wafer manufacture, there is a need for ultra low metallic impurities (ppb levels) for any processing material or liquid that will contact the wafer in order to avoid affecting the electrical properties of the integrated circuits being produced.
It would be desirable to produce amidoxime compounds which have extremely low metals concentrations for use as a component in compositions used in semiconductor processes.